Xylem tissue is composed of

Which of the following organisms is not correctly matched with its taxonomic category?

In an emission spectrum,the transitions $n_2 \to n_1, n_3 \to n_1, n_4 \to n_1, n_5 \to n_1$ result in the emission of energies $E_1, E_2, E_3, E_4$ respectively. What is the increasing order of these energies?

Which one of the following is correct?

Two thermometers $X$ and $Y$ have ice points marked at $15^o$ and $25^o$ and steam points marked as $75^o$ and $125^o$ respectively. When thermometer $X$ measures the temperature of a bath as $60^o$ on it,what would thermometer $Y$ read when it is used to measure the temperature of the same bath?

The set $\{x \in R: \cos 2x + 2 \cos^2 x = 2\}$ is equal to